This invention relates essentially to watches with electronic movements and, more particularly, to watches of this type which comprise dual display means.
Display means in watches are generally classified as analog and digital.
Analog displays, or in other words, those in which the hourly information is shown by means of hands moving in front of a dial and driven by an electric motor through a transmission mechanism, offer the advantages of great ease of reading and better aesthetic properties. However, with this type of display it is not possible to show the complex functions performed more and more by modern watches.
Digital displays, which reflect hourly information in the form of digits, offer considerable flexibility of use, making it possible, for example, to display a large number of functions (such as, for example, hour, minute, second, day, month, a number of time zones, chronograph, countdown, alarm, etc.). Unfortunately, rapid reading of such displays is difficult due to practical reasons relating to imperfections in the cells used up to the present time (contrast, directivity) as well as the need to read a group of digits rather than viewing the simple position of watch hands. Further, such displays are only available recently, and the use of these displays in very elegant watches causes aesthetic problems.
It is for this reason that numerous attempts have been made to reconcile the advantages of the two types of displays, notably by integrating two different displays within the same watch.
The most common solution consists in providing one of each type of display means on the same watch face. Thus, there are analog-digital watches in which a window through which a liquid crystal (LC) cell can be seen is provided in the dial of an analog display. Additionally, there are digital-analog watches in which a small-sized-analog display is juxtaposed with a digital display system. Although it is possible, with this solution, to combine the practical advantages of both types of display, such a solution in no way solves the aesthetic problems, but introduces an additional power problem, due to the fact that it is practically necessary at all times to feed the two displays that appear simultaneously to the wearer.
According to another solution, described, for example, in Japanese patent application No. 53-929271 published under No. 5518990 for Suwa Seikosha, K.K., a watch has a display on each face, one being digital and the other analog. The watch can be worn in such a way that either one or the other face appears to the wearer. A solution which is of the same type, although it pertains to two analog displays, is described in Swiss Pat. No. 408 794, which shows a timepiece comprising a watch band with two usable surfaces supporting two watches that are not superimposed. The watches are turned with respect to the watch band in such a way that, depending whether one or the other face of the band is in contact with the wrist, the dial of the other watch is visible. In this case, the aesthetics of the watch can be preserved as long as it is the analog display of the watch that is presented for view. But switching from one display to the other is not convenient nor instantaneous, as is desirable, when the wearer simply wishes to check the date on the digital display, for example. Furthermore, this type of design requires a special type of watch band. Additionally, a watch case structure comprising a display on each face is not satisfactory because of structural limitations or ease of access to the members forming the movement.